Guarini has yet to respond via his Twitter account. But then his fingers are probably still messy from applying balm to that sick burn Clarkson just laid on him.

11 Best 'American Idol' Performances of All Time (Videos)

Arguably the most successful "Idol" alum, Carrie Underwood has come a long way since winning Season 4, and her performance of Heart's "Alone" was an early look at the power and confidence that would define her career in the years to come.

Candice Glover stunned the "Idol" judges and audience with her rendition of The Cure's "Lovesong" on Season 12. Showcasing vocals more headline-worthy than the season's Nicki Minaj-Mariah Carey feud, Glover sealed her fate as the eventual winner.

Adam Lambert's impressive cover of Tears for Fears' "Mad World" cemented his status as Season 8's obvious frontrunner, making it all the more shocking when Kris Allen walked away victorious.

The natural star power that helped Kelly Clarkson's career skyrocket after winning Season 1 was never more apparent than when she killed her performance of Aretha Franklin's "(You Make Me Feel Like) A Natural Woman."

Though she was eventually bested by Phillip Phillips, Jessica Sanchez ruled the "Idol" stage with a voice beyond her young years. Never was that more true than in her commanding Season 11 performance of the "Dreamgirls" torch song, "And I Am Telling You I'm Not Going."

By the penultimate episode of Season 8, Kris Allen seemed like a long-shot to make it to the finale. But by putting his own spin on Kanye West's "Heartless," Allen won over fans and came out on top, besting frontrunner Lambert.

Though no one could have predicted that Jennifer Hudson would go on to win an Oscar, when the Season 3 contestant easily nailed Elton John's "Circle of Life," it was apparent that she was destined for greater than her eventual seventh-place finish.

Former back-up singer Melinda Doolittle didn't win Season 6, but her early performances, including a stellar rendition of Ella Fitzgerald's "My Funny Valentine," proved she had the refined talent of a seasoned pro.

Fantasia Barrino's performance of "Summertime" is such an iconic moment in "Idol's" 15-season run that the show brought the Season 3 winner back to perform the Ella Fitzgerald song on its farewell season.

Pint-sized powerhouse Haley Reinhart delivered a couple amazing performances during her run on Season 10, but her flawless cover of The Animal's "House of the Rising Sun" cover is what best cements the third-place finisher's status as the season's obvious standout.

In the Final 2 episode of Season 11, Phillip Phillips debuted his soon-to-be ubiquitous (thanks to the 2012 Summer Olympics) single "Home." The stirring performance won Phillips the crown and made him a household name.

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From Kelly Clarkson’s Aretha Franklin cover to Adam Lambert’s take on Tears for Fears, we look back at highlights from the show’s 15 seasons on Fox ahead of its ABC reboot

Arguably the most successful "Idol" alum, Carrie Underwood has come a long way since winning Season 4, and her performance of Heart's "Alone" was an early look at the power and confidence that would define her career in the years to come.